When would you ever promote a melee minion?
If you want to tank the turret, you always pick cannon because it has the most EHP.
If you want extra dps on the turret, you always pick caster because it has the highest dps.
Make a promoted melee minion into a NINJA minion. Ninja minions use energy for their melee abilities and use the power of the shadow to distract towers into attacking other melee minions while assassinating towers from behind. They also gain additional health regen when Zed is nearby.
